There have been a significant number of researches on computational fluid dynamic (CFD) analysis of balls used in sports such as golf balls, tennis balls, and soccer balls. Sepak takraw is a high speed court game predominantly played in Southeast Asia using mainly the legs and head. The sepak takraw ball is unique because it is not enclosed and made of woven plastic. Hence a study of its aerodynamics would give insight into its behaviour under different conditions of play. In this study the dynamics of the fluid around a static sepak takraw ball was investigated at different wind speeds for three different orientations using CFD. It was found that although the drag did not differ very much, increasing the wind velocity causes an increase in drag. The lift coefficient varies as the velocity increases and does not show a regular pattern. The drag and lift coefficients are influenced by the orientation of the sepak takraw ball.

It has been shown in previous studies that the flight trajectories of sports balls are influenced by their aerodynamic characteristics. These aerodynamic characteristics are primarily dependent on the physical shape and surface texture of the balls. Even though sepak takraw is well established as a sport, little is known regarding the aerodynamic characteristics of the sepak takraw ball, which has a rather complex shape and surface texture. Hence, the main objective of this research is to investigate the aerodynamic characteristics (specifically the drag and lift coefficients) and flow features of a modern sepak takraw ball commercially available in the market by means of numerical simulations and wind tunnel experiments using the smoke flow visualization technique. The aerodynamic characteristics and flow features of the ball are determined for non-spinning conditions at a wind speed of 3 m/s. It is found that the drag coefficient and lift coefficient of the sepak takraw ball is 0.4868400 and -0.0130915, respectively. The images captured from the smoke flow visualization experiments reveal that the sepak takraw ball is in the subcritical flow regime at a wind speed of 3 m/s, which is the regime before the drag crisis. The laminar boundary layer separates from the upper and lower surfaces of the ball at points upstream of the equator of the ball, creating a large wake region downstream of the sepak takraw ball and resulting in high drag. This in turn, influences the trajectory of the sepak takraw ball in flight. The flow features observed from the smoke flow visualization experiments are representative of the flow during a sepak takraw game. Owing to the complexity of sepak takraw ball, it is recommended that the aerodynamic characteristics of the sepak takraw ball are investigated for spinning conditions in future studies.

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